The lip profile after correction of retromaxillism in cleft and non-cleft patients.

Based on 25 cases with unilateral cleft of lip, alveolus and palate with retromaxillism (CLAP) and 25 cases with pure retromaxillism (RM), the effect on the lip of advancing the maxilla by Le Fort I osteotomy is analysed. It can be shown that on average the base of the upper lip follows the base of the maxilla in a ratio of 4:7. The free end of the upper lip is pushed forwards by the upper front teeth in a ratio of 5:9. This means that to achieve a specified lip advancement, the maxilla has to be brought forward about double the amount. No important between CLAP and RM could be seen. Leaving the nasal spine intact has a favourable influence on movements of the upper lip. The amount of maxillary advancement has no bearing on the ratios. It seems though that thin lips follow the movement of the maxilla better than voluminous lips. There is no satisfactory explanation why the extremes in all groups for all measurements are placed so very far apart. This leads to the conclusion that in spite of careful planning the result in the individual case can differ considerably from that expected.